The Immunology Core will provide all immunological assays used in common among Projects 1 through 4. The Immunology Core will evaluate cell phenotypes and immune responses during vaccination and after virus challenge. These results, in conjunction with the evaluations made by the Virology Core, will be used by the projects to characterize the immune responses to the different vaccines and to identify correlates of protective immunity. There are three specific aims. Aim 1. To serve as a receiving point for rhesus macaque blood specimens drawn by the IHV division of Animal Models, coding, cataloguing and processing these specimens for distribution to the Immunology and Virology Cores or archiving processed specimens, as appropriate, for eventual distribution. Specimens processing will including isolating PBMCs and plasma from heparinized or citrate-treated peripheral blood flow by Ficoll-Hypaque density gradient centrifugation. Aim 2. To perform studies of rhesus macaque cell phenotype and lymphocyte function. Studies will include: a. flow cytometry evaluations of the surface phenotypic markers CD3 (pan T cell), CD4 (T cell subset), CD8 (T cell subset), CD20 (B cells), and CD14 (monocytes), b. determinations of polyclonal and antigen specific proliferative responses, c. preparing and harvesting culture supernatants from T cells activated by polyclonal or antigen-specific stimuli for chemokine production by ELISA, d. preparing and harvesting culture supernatants from T cells activated by polyclonal or antigen-specific stimuli for virus suppressor factors (VSFs), e. HIV or SIV-specific cytotoxic T lymphocyte (CTL) assays f. to evaluate the presence of virus- specific serum antibodies by ELISA or Western blot analysis, Aim 3. To collate data from assays initiated by the Immunology Core and Transmit it to the Project Leaders and the Administrative Core.